The present invention relates to an isolating cover for transformer, and more particularly to a cover for transformer to increase creepage distances between bobbin and frame core of the transformer in all directions. The isolating cover for transformer is a plastic member integrally formed by injection molding and includes many isolating walls at different positions thereon to completely prevent a hipot from directly crossing over a conductive metal component between high-tension and low-tension ends. The isolating cover can be easily assembled to the transformer to protectively cover a top of the bobbin and can therefore replace a conventionally used insulating tape. The transformer can therefore have simplified manufacturing process and improved quality.
Transformers are required components in electronic circuits. Since circuit boards used in the existing electronic products are very thin, small and light in volume, transformers used for constructing the circuit boards must also have largely reduced size. However, all transformers mainly structurally include a bobbin, multiple pins, at least a core, and at least a winding. With different arrangements of these components, transformers of different shape, specification and function may be produced.
Wherein, the winding may be a dual winding including an inner and an outer windings or a multi-slot winding, and the core may be formed from two E-shaped members or a central I core and a frame core. While transformers may be differently structured, they all have to comply with relevant safety codes specifying safe and protective requirements thereof. Among the safety codes, there is one particularly concerning "creepage distance". The creepage distance may be 1.6 mm, 2.5 mm or other length, depending on grades, such as A or B grade, specified in the safetycodes. The purpose of creepage distance is to define a safety distance between two metal components so as to prevent a hipot at a high-tension end from directly crossing over a conductive metal component to a lower-tension end and resulting in damages, such as short circuit, to circuit at the low-tension end. Such safety distance must exist in many areas on a transformer, including areas between the winding and the core, the pins and the winding, and/or the pins and the core.
For the currently commercially available transformers of different specifications, there are different isolating means separately provided to achieve required safety distances between different components. However, being limited by the required small volume of transformer, such isolating means are usually designed only to increase the creepage distance at a certain particular area of the transformer and do not have other functions.